Abstract: The NO_x emission of gas turbine is unstable due to the environment influence in the operation of gas turbine, the environmental humidity is one of the factors influencing the NO_x emission of gas turbine. At the low humidity condition, the NO_x emission of the gas turbine is liable to be excessive.Considering the relative humidity of NO_x emission influential factor, a kind of air intake humidification device was installed in the air intake system of the gas turbine to reduce the NO_x emission of the heavy gas turbine in the dry environment. The practical operation verified that the improved method can effectively reduce the NO_x emission during a certain load condition.